Final answer:
The two isomers of [Co(NH₃)₅(NO₂)]Cl₂ have different colors due to linkage isomerism of the NO₂ ligand. They demonstrate how changes in ligand attachment can affect a compound's physical and optical properties, with the statement in the question being true.
Step-by-step explanation:
Two isomers of [Co(NH₃)₅(NO₂)]Cl₂ do indeed exhibit different colors due to the linkage isomerism of the NO₂ ligand, which can bind through nitrogen (nitro) or oxygen (nitrito). Linkage isomers have the same molecular formula but differ in the atom of the ligand that coordinates to the metal center. This change in bonding can cause a significant difference in the optical properties of the compounds, leading to the observed color change.
The concept of isomerism, in this context, is similar to the geometric isomerism seen in [Co(NH₃)4Cl₂]NO₃, where the cis form is violet while the trans form is green. These isomers not only differ in color but also in other physical and chemical properties such as dipole moments, solubilities, and reactivities.
Therefore, the statement regarding the color difference in the two isomers of [Co(NH₃)₅(NO₂)]Cl₂ as a result of different linkage isomers is true; hence, the answer is 1.